Abstract

The aim of the work presented in this thesis was to assess the genetic variation present within the wild tomato species Solanum pennellii that can be adapted to improve the texture of the domesticated tomato species. Using a population of S. pennellii introgression lines, 23 significant QTL supporting intervals were identified. Nine of the QTL were significant in two growing seasons. Three QTL were identified for pericarp firmness. Lines containing the firmness QTL F-Sp 2.1 were used to create BC1 populations. Sensory analyses were used to correlate the instrumental texture measurements to those perceived during mastication. Repeated texture measurements were conducted on lines representing similar chromosomal regions from another wild tomato species Solanum habrochaites introgression line population. To better understand the genetic basis of one of the firmness QTL identified, the Syngenta tomato Affymetrix GeneChip was used to quantify the differential expression of S. pennellii genes within the QTL-introgression line through development in comparison to the recurrent parent S. lycopersicum L. cv M82. The microarray analyses were extended to the ripening mutants Cnr, nor and rin. Differential gene expression between the ripening mutants and the wild type Ailsa Craig were compared through development. Candidate genes for the firmness QTL and fruit development were nominated.